To continue our research on the physiological correlates of sexual behavior in male cats we are presently investigating the effects of lesions in the lateral amygdala and periamygdalar cortex with particular reference to the often described phenomenon of hypersexuality. In addition to the widely used standard sex tests, the subjects were given special 1-hour selection tests. In this test the males were presented with a stuffed toy, a tranquilized rabbit, a lightly sedated male and finally, the same female as was used in the standard test. Postoperatively in the standard tests there were no indications of hypersexuality. In the selection tests there was a significant increase in the mounting of the reproductively less appropriate objects. That is, there was a loss in selectivity. This change is not interpreted as hypersexuality, but rather as a change in behavior resulting from the decrements in visual perception. To localize the critical area we are now restricting our lesions to the periamygdalar cortex and in a third experiment using the same experimental design, we will ablate the medial amygdala nuclei. BIBLIOGRAPHIC REFERENCES: Cooper, Madeline L. and Lester R. Aronson. Factors involved in the selection of a female mating partner by the male domestic cat. American Zoologist, 15 (3): 813. (1975). Aronson, Lester R. and Madeline L. Cooper. Hypersexuality following amygdala lesions in male cats reexamined. Anatomical Record, 184(3): 346-347. (1976).